A powerful October storm system has dumped heavy rainfall across Southern California, with San Luis Obispo County receiving approximately 1.5 inches, Santa Barbara County about an inch, and Ventura County's mountains collecting roughly an inch, according to the National Weather Service. Los Angeles County has seen between one-tenth and a quarter inch so far.
Evacuation warnings were issued for the Palisades burn scar area and the National Weather Service also issued a thunderstorm warning for the western portion of Los Angeles County saying wind gusts could reach 60 miles per hour. However, as of Tuesday morning, little damage had been reported aside from a water main break and tree debris.
Forecasters expect total rainfall amounts to reach between 0.75 and 1.50 inches across most areas by the time the storm ends, with south-facing slopes potentially receiving 2.00 to 4.00 inches. The rain is forecast to diminish and end by late afternoon and early evening today.
The strong cold front associated with an early season low-pressure system is currently moving through the region, bringing widespread rain with isolated heavy downpours and scattered thunderstorms. The front entered Santa Barbara city between 3:30 a.m. and 5 a.m., moved into Ventura County around 5 a.m. and exited by 8 a.m., then entered Los Angeles County around 6 a.m. and is expected to exit by 10 a.m.
Peak rainfall rates in and near the front have ranged from 0.5 to 1.00 inch per hour, creating significant risks of debris flows and road flooding, particularly over and near first- and second-year burn scars. A flash flood watch remains in effect for these burn scar areas, and officials are urging residents living nearby to closely monitor weather conditions and heed warnings from emergency personnel.
The storm has also produced severe weather conditions. An unusually strong jet stream for October — with winds reaching 100 knots — combined with atmospheric instability has created a favorable environment for low-topped severe thunderstorms. Several severe storms have already been detected by Doppler weather radar, and forecasters warn more are likely as the system continues moving through the area.
Gusty winds are accompanying the storm, with mountain and desert areas experiencing advisory-level gusts of 45 to 55 mph. Snow is falling at resort levels above 7,000 feet, though major mountain passes remain unaffected.
High temperatures today will only reach the lower to mid-60s, running 12 to 24 degrees below normal for mid-October — temperatures that would typically be below normal even for January.
Relief is on the way as clearing conditions develop from west to east during the afternoon and early evening, bringing dry conditions and mostly clear skies.
Wednesday will bring sunny and dry weather with temperatures climbing 5 to 10 degrees as dry northwest flow moves around the departing upper low. The warming trend will continue Thursday, with another 5 to 10 degree temperature increase expected under sunny skies. Dry conditions and the warming trend are forecast to persist through Saturday.
Moderate offshore flow from the north is expected to develop Wednesday and continue into Thursday morning, possibly bringing some northerly to northeasterly winds, though they are likely to remain below advisory levels.